Fix animation while hiding Desktop tasks during split

1. Scale down desktop tasks
2. Change translation start when all desktop tasks need to hidden

Fix: 378447894
Flag: com.android.launcher3.enable_large_desktop_windowing_tile
Test: Manual: Add desktop window and split focussed task, desktop task(s)(also in RTL)
Change-Id: I25c11d654539efc6529a2e995d8d00cbf73c870d